Walnuts for Cardiovascular Health

Overseen By Tatiana Diacova, MS, RDN

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of California, Davis

Must not be taking: Metformin, Statins, Antibiotics, others

Disqualifiers: Diabetes, Renal disease, Smoker, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 5

30 Participants Needed

Trial Summary

Will I have to stop taking my current medications?

If you are taking medications or supplements that affect metabolism or gut bacteria, like Metformin, statins, or antibiotics, you may need to stop them to participate in this trial. The protocol does not specify a washout period, but these medications are part of the exclusion criteria.

What data supports the effectiveness of the treatment 'Walnuts for Cardiovascular Health'?

Research shows that eating walnuts can help lower bad cholesterol (LDL) and total cholesterol, which are linked to heart disease. Regular walnut consumption is also associated with overall heart health benefits, making them a good addition to a heart-healthy diet. ^{1 2 3 4 5}

Is walnut consumption safe for humans?

Walnut consumption is generally considered safe for humans and has been associated with various health benefits, including improved cholesterol levels and reduced blood pressure, which are important for heart health. ^{1 5 6 7 8}

How does the walnut treatment for cardiovascular health differ from other treatments?

The walnut treatment is unique because it involves consuming walnuts, which are rich in polyunsaturated fatty acids and antioxidants, to improve heart health by lowering bad cholesterol and blood pressure. Unlike traditional medications, this approach uses a natural food source to target multiple cardiovascular risk factors simultaneously. ^{5 6 7 8 9}

What is the purpose of this trial?

The purpose of this research is to test if eating walnuts will cause any changes in blood lipids (like good and bad cholesterol, for example) and levels of inflammation in the blood, as well as changes in the bacteria living in the gut.

Eligibility Criteria

This trial is for overweight and obese men and postmenopausal women aged between 45-70, with a BMI of 25.0-39.9 kg/m2 and higher levels of 'bad' cholesterol (LDL-C between 130-189 mg/dL).

Inclusion Criteria

I am 45-70 years old, overweight or obese, and have high LDL cholesterol levels.

Timeline

Screening

Participants are screened for eligibility to participate in the trial

1 week

1 visit (in-person)

Run-in

Participants undergo a 1-week run-in period to become accustomed to the study diet

1 week

1 visit (in-person)

Diet Intervention 1

Participants follow either a walnut or no-nut diet for 3 weeks

3 weeks

1 visit (in-person)

Washout

Participants undergo a 3-week washout period between diet interventions

3 weeks

1 visit (in-person)

Diet Intervention 2

Participants switch to the alternate diet (walnut or no-nut) for 3 weeks

3 weeks

1 visit (in-person)

Follow-up

Participants are monitored for changes in cardiometabolic biomarkers and gut microbiota

1 week

Treatment Details

Interventions

• No-nut diet
• Walnuts

Trial Overview The study is examining the effects of eating walnuts on heart health markers like good and bad cholesterol, inflammation in the blood, as well as gut bacteria compared to a no-nut diet.

Participant Groups

Group I: No-nut diet Active Control 1 Intervention

Participants will follow a no-nut diet for 3 weeks.

Group II: Walnut diet Active Control 1 Intervention

Participants will consume 56 g of walnuts each day at home for 3 weeks.

Who Is Running the Clinical Trial?

University of California, Davis

Lead Sponsor

Trials

958

Recruited

4,816,000+

Findings from Research

In a study involving 40 healthy participants aged 50 and older, consuming 43g of walnuts daily for 8 weeks significantly reduced non-HDL cholesterol and apolipoprotein-B levels, which are important markers related to heart disease risk.

Despite these positive changes in cholesterol levels, other factors such as fasting glucose, insulin, and markers of inflammation and endothelial function did not show significant changes, indicating that walnuts may specifically target lipid profiles without affecting other metabolic parameters.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Walnut-enriched diet reduces fasting non-HDL-cholesterol and apolipoprotein B in healthy Caucasian subjects: a randomized controlled cross-over clinical trial. Wu, L., Piotrowski, K., Rau, T., et al.[2022]

A systematic review and meta-analysis of 139 studies found that consuming tree nuts and peanuts significantly reduces several cardiovascular disease (CVD) risk factors, including LDL cholesterol, total cholesterol, and triglycerides.

Despite the positive findings, the overall quality of evidence was low for many outcomes, indicating that while nuts can contribute to CVD risk reduction, further high-quality research is needed to confirm these benefits.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Tree Nut and Peanut Consumption and Risk of Cardiovascular Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Houston, L., Probst, YC., Chandra Singh, M., et al.[2023]

A meta-analysis of 13 randomized controlled trials involving walnut intake showed significant reductions in total cholesterol (TC), low-density lipoprotein (LDL-C), and triglycerides (TG), indicating that walnuts can improve blood lipid profiles and potentially reduce cardiovascular disease risk.

The study found that individuals who were overweight or had comorbidities experienced greater improvements in lipid levels with walnut consumption, suggesting that walnuts may be particularly beneficial for these populations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The Effect of Walnut Intake on Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Alshahrani, SM., Mashat, RM., Almutairi, D., et al.[2022]

In a study involving 45 individuals at risk for cardiovascular disease, a walnut diet led to a significant reduction in central diastolic blood pressure compared to a diet where walnut-derived ALA was replaced with oleic acid, suggesting that whole walnuts may provide unique cardiovascular benefits beyond just their fatty acid content.

All diets tested, including the walnut diet, resulted in lowered total cholesterol and LDL cholesterol levels, indicating that moderate-fat, high-unsaturated-fat diets can improve overall cardiovascular risk factors.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Replacing Saturated Fat With Walnuts or Vegetable Oils Improves Central Blood Pressure and Serum Lipids in Adults at Risk for Cardiovascular Disease: A Randomized Controlled-Feeding Trial. Tindall, AM., Petersen, KS., Skulas-Ray, AC., et al.[2021]

References

1. United States pubmed.ncbi.nlm.nih.gov

Walnut-enriched diet reduces fasting non-HDL-cholesterol and apolipoprotein B in healthy Caucasian subjects: a randomized controlled cross-over clinical trial. [2022]

2. Netherlands pubmed.ncbi.nlm.nih.gov

Walnut consumption and cardiac phenotypes: The Coronary Artery Risk Development in Young Adults (CARDIA) study. [2022]

3. United States pubmed.ncbi.nlm.nih.gov

Tree Nut and Peanut Consumption and Risk of Cardiovascular Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. [2023]

4. Switzerland pubmed.ncbi.nlm.nih.gov

Effects of Supplementing the Usual Diet with a Daily Dose of Walnuts for Two Years on Metabolic Syndrome and Its Components in an Elderly Cohort. [2020]

5. Switzerland pubmed.ncbi.nlm.nih.gov

The Effect of Walnut Intake on Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. [2022]

6. United States pubmed.ncbi.nlm.nih.gov

Walnuts decrease risk of cardiovascular disease: a summary of efficacy and biologic mechanisms. [2023]

7. England pubmed.ncbi.nlm.nih.gov

Replacing Saturated Fat With Walnuts or Vegetable Oils Improves Central Blood Pressure and Serum Lipids in Adults at Risk for Cardiovascular Disease: A Randomized Controlled-Feeding Trial. [2021]

8. United States pubmed.ncbi.nlm.nih.gov

Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review. [2023]

9. Thailand pubmed.ncbi.nlm.nih.gov

Antioxidant activity comparison of walnuts and fatty fish. [2012]